[Papanicolau smears: reducing the false negative rate by improving the method]

Screening for cervical carcinoma precursors by Papanicolau (Pap) smears diminishes the incidence of cervical cancer in screened populations. The Pap smear test has a considerable rate of false negatives and in order to improve its efficiency and sensitivity several types of technologies were developed, two of which are discussed in this review. One entails measures for collecting cells from the cervix into a liquid medium and preparing single layer smears from these cells. Using this method, a thin and clean smear is obtained, in comparison to the regular Pap smear. The liquid-based test improves sample adequacy and increases the diagnostic accuracy of low-grade and high-grade squamous intraepithelial lesions. The second type of technology is computerized deciphering of cervical smears, which are prepared either by the regular method or using the previously mentioned thin smear. the computerized deciphering is based on structural measurements of cells via an instrument that is programmed to differentiate between cellular components, thus categorizing the smears into those which are normal and those that require further evaluation by a cytopathologist. Alternatively the computer can display the most abnormal cells in the smear to the cytopathologist. In this manner, the workload of the cytopathologist is reduced while the test efficiency and sensitivity are increased.